Technical Field of the Invention
A self-tapping screw is known from EP 0 623 759 B1, in which the ratio which the major diameter bears to the minor diameter is approximately 1.25-1.5, the ratio which the major diameter bears to the pitch lead is approximately 1.5-1.6 and the flank angle of the thread is &lt;50.degree. and &gt;35.degree..
EP 0 433 484 B1 teaches a self-tapping screw, the thread of which is provided with cutting teeth of approximately bowed design, the central cutting edge being level with the crest of the thread and set negatively.